Abstract

Near-infrared (NIR) and electroencephalography (EEG) systems were applied simultaneously to check a possibility of an optical brain-computer interface (BCI) based on visual protocol. A two-wavelength, two-channel NIR system using lock-in amplifiers to filter received signal was designed for monitoring of light absorption. An improved single photon-counting system based on NIR laser diodes and multichannel scaling was configured for fast one-wavelength capturing of the scatter changes in the area of the human brain corresponding to the task. Designed protocols consisted of the pattern reversed repeatedly at various frequencies. The stimulus repetition improves processing according to some behavioural measure as e.g. greater accuracy in identifying the stimulus or faster response times to make a decision about it, and often occurs under the same experimental conditions. Under certain conditions rather increased activity in the brain could be observed which results in a longer habituation time. Results of tests are presented in current article.